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Biomedical subjects

Douglas L Weed

Publications and source records attributed to Douglas L Weed.

17 recordsLinked to original sources
PubMed2006

Two Surgeon General's reports on smoking and cancer: a historical investigation of the practice of causal inference.

BACKGROUND: The epidemiologic literature is replete with conceptual discussions about causal inference, but little is known about how the causal criteria are applied in public health practice. The criteria for causal inference in use today by epidemiologists have been shaped substantially by their use over time in reports of the U.S. Surgeon General on Smoking and Health. METHODS: We reviewed two classic reports on smoking and health from expert committees convened by the US Surgeon General, in 1964 and 1982, in order to evaluate and contrast how the committees applied causal criteria to the available evidence for the different cancer sites at different time periods. We focus on the evidence for four cancer sites in particular that received detailed reviews in the reports: lung, larynx, esophagus and bladder. RESULTS: We found that strength of association and coherence (especially dose-response, biological plausibility and epidemiologic sense) appeared to carry the most weight; consistency carried less weight, and temporality and specificity were apparently not applied at all in some cases. No causal claim was made for associations with a summary odds ratio of less than 3.0. CONCLUSION: Our findings suggest that the causal criteria as described in textbooks and the Surgeon General reports can have variable interpretations and applications in practice. While the authors of these reports may have considered evidential factors that they did not explicitly cite, such lack of transparency of methods undermines the purpose of the causal criteria to promote objective, evidence-based decision making. Further empirical study and critical examination of the process by which causal conclusions are reached can play an important role in advancing the practice of epidemiology by helping public health scientists to better understand the practice of causal inference.

Journal Article↗
PubMed2006

Evaluating research training outcomes: experience from the cancer prevention fellowship program at the National Cancer Institute.

PURPOSE: The authors describe an evaluation approach to assess research training that is easy to implement, takes into account individual experience and diversity in research disciplines, and can be adapted to measure various outcomes, depending upon program goals. METHOD: Using publications as the outcome measure, the authors analyzed data from 66 trainees in the National Cancer Institute's Cancer Prevention Fellowship Program (CPFP) to illustrate this evaluation strategy. For postdoctoral fellows entering the CPFP between 1987 and 1997, the authors considered the three-year period prior to entry in the CPFP (pre-CPFP), the period during training, and the three-year period after completion of the CPFP (post-CPFP). Summary measures for individuals' publications during each of the three time periods were calculated, and the probability of change in total, peer-reviewed, and first-authored publications post-CPFP compared to pre-CPFP was assessed. RESULTS: Compared to pre-CPFP, the CPFP fellows published significantly more total, peer-reviewed, and first-authored publications post-CPFP. Post-CPFP younger individuals published more than older fellows. MDs had a greater increase in publications over time than did PhDs, but both groups had similar overall numbers of publications post-CPFP. Individuals pursuing a master of public health degree during training published more post-CPFP than did those who did not pursue this training in the program. CONCLUSIONS: Training programs facing the challenge of evaluating research outcomes will require new evaluation methods that take into account program goals. This easily adaptable, longitudinal evaluation strategy allows for diversity in research disciplines and research experience and can inform programmatic needs and individual progress.

Adult↗
PubMed2005

Adapting postdoctoral training to interdisciplinary science in the 21st century: the Cancer Prevention Fellowship Program at the National Cancer Institute.

Preparing junior scientists for careers in the health sciences has become an immense challenge for many reasons, including the emerging demand for multidisciplinary approaches to solving problems in the health sciences. For those choosing careers in hybrid and interdisciplinary fields, the "traditional" postdoctoral training model may not perform well, particularly in light of other problems that plague postdoctoral success. New approaches are required. Using the interdisciplinary field of cancer prevention as an example, the authors describe the Cancer Prevention Fellowship Program (CPFP) of the National Cancer Institute, a three-year postdoctoral program of which the goal is to provide its fellows with a strong foundation in cancer prevention through education, mentored research, and structured professional development training activities that emphasize multidisciplinary approaches and leadership skills. Over time, the CPFP has incorporated the best aspects of the traditional postdoctoral training model with newer training approaches in an effort to overcome existing problems in postdoctoral training and to address the additional complexities inherent in training those who seek careers in interdisciplinary science. Many aspects of the CPFP, including an efficient infrastructure, a dedicated staff, a capacity to provide educational activities, and the provision of rich research opportunities, may translate well to other postdoctoral programs that face similar issues.

Education, Medical, Graduate↗
PubMed2005

Weight of evidence: a review of concept and methods.

"Weight of evidence" (WOE) is a common term in the published scientific and policy-making literature, most often seen in the context of risk assessment (RA). Its definition, however, is unclear. A systematic review of the scientific literature was undertaken to characterize the concept. For the years 1994 through 2004, PubMed was searched for publications in which "weight of evidence" appeared in the abstract and/or title. Of the 276 papers that met these criteria, 92 were selected for review: 71 papers published in 2003 and 2004 (WOE appeared in abstract/title) and 21 from 1994 through 2002 (WOE appeared in title). WOE has three characteristic uses in this literature: (1) metaphorical, where WOE refers to a collection of studies or to an unspecified methodological approach; (2) methodological, where WOE points to established interpretative methodologies (e.g., systematic narrative review, meta-analysis, causal criteria, and/or quality criteria for toxicological studies) or where WOE means that "all" rather than some subset of the evidence is examined, or rarely, where WOE points to methods using quantitative weights for evidence; and (3) theoretical, where WOE serves as a label for a conceptual framework. Several problems are identified: the frequent lack of definition of the term "weight of evidence," multiple uses of the term and a lack of consensus about its meaning, and the many different kinds of weights, both qualitative and quantitative, which can be used in RA. A practical recommendation emerges: the WOE concept and its associated methods should be fully described when used. A research agenda should examine the advantages of quantitative versus qualitative weighting schemes, how best to improve existing methods, and how best to combine those methods (e.g., epidemiology's causal criteria with toxicology's quality criteria).

Epidemiology↗
PubMed2004

Precaution, prevention, and public health ethics.

The precautionary principle brings a special challenge to the practice of evidence-based public health decision-making, suggesting changes in the interpretative methods of public health used to identify causes of disease. In this paper, precautionary changes to these methods are examined: including discounting contrary evidence, reducing the number of causal criteria, weakening the rules of evidence assigned to the criteria, and altering thresholds for statistical significance. All such changes reflect the precautionary goal of earlier primary preventive intervention, i.e. acting on insufficient evidence, the least amount, or minimum level, of evidence for causation. Evaluating the impact of these changes will be difficult without a careful study of how well the current methods of causal inference work, their theoretical foundations, and the ethical implications of their applications. That research program will be most productive if it is jointly developed by public health professionals trained in the ethics and philosophy and by bioethicists and philosophers trained in the theories, methods, and practice of public health.

Bioethical Issues↗
PubMed2004

Methodologic implications of the Precautionary Principle: causal criteria.

Applying the Precautionary Principle to public health requires a re-evaluation of the methods of inference currently used to make claims about disease causation from epidemiologic and other forms of scientific evidence. In current thinking, a well-established, near-certain causal relationship implies highly consistent statistically significant results across many different studies, large relative risk estimates, extensive understanding of biological mechanisms and dose-response relationships, positive prevention trial results, a clear temporal relationship between cause and effect, and other conditions spelled out in terms of the widely-used causal criteria. The Precautionary Principle, however, states that preventive measures are to be taken when cause and effect relationships are not fully established scientifically. What evidentiary conditions, as reflected in the causal criteria, will be certain enough to warrant precautionary preventive action? This paper argues that minimum evidentiary requirements for causation need to be articulated if the Precautionary Principle is to be successfully incorporated into public health practice. Two precautionary changes to criteria-based methods of causal inference are examined: reducing the number of criteria and weakening the rules of inference accompanying the criteria. Such changes point in the direction of identifying minimum evidentiary conditions, but would be premature without better understanding how well current methods of causal inference work.

Environmental Pollutants↗
PubMed2003

American College of Epidemiology Ethics Guidelines: foundations and dissemination.

Epidemiology is a core science of public health, focusing on research related to the distribution and determinants of both positive and adverse health states and events and on application of knowledge gained to improve public health. The American College of Epidemiology (ACE) is a professional organization devoted to the professional practice of epidemiology. As part of that commitment, and in response to concerns for more explicit attention to core values and duties of epidemiologists in light of emerging issues and increased scrutiny of epidemiology, the College developed, adopted, and published a set of Ethics Guidelines. The structure of the ACE ethics guidelines is in four parts: (1) a brief statement of core values and duties of epidemiologists, coupled with the virtues important to professional practice; (2) concise statements of key duties and obligations; (3) exposition of the duties and obligations with more applications; and (4) a brief summary and conclusion. The Guidelines have been published on the ACE website and in the official College journal Annals of Epidemiology. The guidelines contain (and maintain) core elements that define the discipline of epidemiology and its fundamental duties, but they are also intended to be dynamic and evolving, responsive to a changing professional and social environment.

Codes of Ethics↗
PubMed2003

Science and social responsibility in public health.

Epidemiologists and environmental health researchers have a joint responsibility to acquire scientific knowledge that matters to public health and to apply the knowledge gained in public health practice. We examine the nature and source of these social responsibilities, discuss a debate in the epidemiological literature on roles and responsibilities, and cite approaches to environmental justice as reflective of them. At one level, responsibility refers to accountability, as in being responsible for actions taken. A deeper meaning of responsibility corresponds to commitment to the pursuit and achievement of a valued end. Epidemiologists are committed to the scientific study of health and disease in human populations and to the application of scientific knowledge to improve the public's health. Responsibility is also closely linked to reliability. Responsible professionals reliably perform the tasks they set for themselves as well as the tasks society expects them to undertake. The defining axiom for our approach is that the health of the public is a social good we commit ourselves to pursue, thus assuming an obligation to contribute to its achievement. Epidemiologists cannot claim to be committed to public health as a social good and not accept the responsibility of ensuring that the knowledge gained in their roles as scientists is used to achieve that good. The social responsibilities of environmental health researchers are conspicuous in the environmental justice movement, for example, in community-based participatory research. Responsibility is an ethical concept particularly well suited to frame many key aspects of the ethics of our profession.

Environment↗
PubMed2002

Environmental epidemiology: basics and proof of cause-effect.

Bringing epidemiology and toxicology together to better understand cause and effect relationships requires attention to several interconnected problems: problems of commitment, complexity, and of communication. The most fundamental of these is commitment as it is reflected in the basic purpose of environmental epidemiology. The purpose of epidemiology is not to prove cause-effect relationships, and not only because scientific proof is elusive. The purpose of epidemiology is to acquire knowledge about the determinants and distributions of disease and to apply that knowledge to improve public health. A key problem, therefore, is how much and what kinds of evidence are sufficient to warrant public health (typically preventive) actions? The assessment of available evidence lays the foundation for the problem of complexity: relevant evidence arrives from toxicologic and epidemiological investigations, and reflects the acquisition of knowledge from many levels of scientific understanding: molecular, cellular, tissue, organ systems, complete organisms (man and mouse), relationships between individuals, and on to social and political processes that may impact human health. How to combine evidence from several levels of understanding will require the effective communication of current methodological practices. The practice of causal inference in contemporary environmental epidemiology, for example, relies upon three largely qualitative methods: systematic narrative reviews, criteria-based inference methods, and (increasingly) meta-analysis. These methods are described as they are currently used in practice and several key problems in that practice are highlighted including the relevance to public health practice of toxicological evidence.

Animals↗
PubMed2002

Roles and responsibilities of epidemiologists.

Two distinct views of the roles and responsibilities of epidemiologists have emerged in a decades-long debate: one keeps professional practice constrained to science; the other adds active participation in public health policymaking. In defense of the narrower view are several claims: that epidemiologists lack expertise in policymaking; that advocating policy adversely affects scientific objectivity; that the limits of epidemiologic science work against translating results into policy; and that participation in policy can bring on personal attacks. In this study, each claim is addressed. Epidemiologists already participate fully in educational, research funding, and editorial policymaking and thereby have an experiential foundation in some of the basics of policymaking. Policymaking can enhance scientific objectivity because it requires not only the use but more importantly the improvement of empirical methods. Finally, the comforts of professional life are not the primary yardsticks of our responsibilities. Arguments in favor of active involvement in public health policymaking are presented. Epidemiologists have been mixing science and policymaking for a long time and there is a strong sense that the benefits of public stewardship outweigh the risks. The American College of Epidemiology's Ethics Guidelines support this view. Active participation in public heath policymaking will, however, require curriculum changes in graduate training programs. With additional training and a broader recognition that public health policymaking is an appropriate professional pursuit, epidemiologists can look to a bright and challenging future in the science and practice of public health.

Epidemiology↗
PubMed1997

Underdetermination and incommensurability in contemporary epidemiology.

In the shadowy world between philosophy of science and ethics lie the paired concepts of underdetermination and incommensurability. Typically, scientific evidence underdetermines the hypotheses tested in research studies, providing neither proof nor disproof. As a result, scientists must judge the weight of the evidence, and in doing so, bring scientific and extrascientific values to bear in their approaches to assessing and interpreting the evidence. When different scientists employ very different values, their views are said to be incommensurable. Less prominent differences represent partial incommensurabilities. The definitions and analyses provided by McMullin and by Veatch and Stempsey lay the foundation for the description of partial incommensurabilities in the current practice of assessing and interpreting epidemiologic evidence. This practice is called "causal inference" and is undertaken for the purpose of making causal conclusions and public health recommendations from population-based studies of exposures and diseases. Following the work of Bayley and Longino, several suggestions are examined for dealing with the partial incommensurabilities found in the general practice of causal inference in contemporary epidemiology. Two specific examples illustrate these ideas: studies on the relationship between induced abortion and breast cancer and those on the relationship between moderate alcohol consumption and breast cancer.

Abortion, Induced↗